Electrolytic water generation device

Abstract

To provide an electrolytic water generation device having an electrolytic cell formed to suppress scale deposition at a cathode.SOLUTION: An electrolytic water generation device (1) comprises an electrolytic cell (10) formed by laminating a plate-shaped anode (11), a mesh electrode (12), a catalyst electrode (13), an ion exchange membrane (14), and a plate-shaped cathode (15), each having an opening at the center, so that these openings communicate to form a central passage portion (16), and is configured to electrolyze water flowing between the anode and the cathode from an outer periphery of the electrolytic cell toward the central passage portion or from the central passage portion toward the outer periphery of the electrolytic cell to generate electrolytic water. The cathode has a water flow groove (20) formed on a side facing the ion exchange membrane for making water flow between the central passage portion and the outer periphery, and this water flow groove is constituted of two types of grooves having different cross-sectional areas.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an electrolyzed water generating device that generates electrolyzed water by electrolyzing water in an electrolysis cell. [Background technology]

[0002] Electrolyzed water generators that generate electrolyzed water with sterilizing properties, such as ozone water and hypochlorous acid water, have been used in the past. For example, the electrolyzed water generator disclosed in Patent Document 1 has an electrolysis cell in which an anode, an ion exchange membrane, and a cathode are stacked. This electrolyzed water generator applies a voltage between the anode and the cathode to electrolyze a portion of the water flowing near the interface between these electrodes and the ion exchange membrane, thereby generating ozone water as electrolyzed water.

[0003] Patent Document 1 also describes that the production of electrolyzed water is stable because the conductivity of the ion exchange membrane is stable when the membrane has sufficiently absorbed water, and that a groove through which water passes is formed on the side of the cathode of the electrolytic cell facing the ion exchange membrane to promote water absorption at the start of water flow. This groove becomes filled with the ion exchange membrane, which has expanded in volume due to water absorption. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6187861 Summary of the Invention [Problem to be solved by the invention]

[0005] On the anode side of the electrolysis cell, ozone, for example, generated by the electrolysis of water, dissolves in the water to form ozone water. On the cathode side, hydroxide ions generated by the electrolysis of water react with the mineral components contained in the water, depositing insulating scale. The main components of the scale are, for example, calcium carbonate and magnesium hydroxide.

[0006] Because electric current does not easily flow through scale, scale accumulation on the ion exchange membrane side of the cathode inhibits water electrolysis. For example, in electrolyzed water generators that operate at a constant voltage, applying a constant voltage between the electrodes, scale accumulation reduces the efficiency of electrolyzed water production. Furthermore, in electrolyzed water generators that operate at a constant current, adjusting the applied voltage so that a constant current flows between the electrodes, scale accumulation increases the applied voltage, promoting reactions in areas where scale is not accumulated. This accelerates scale accumulation and reduces the durability of the electrolyzed water generator.

[0007] To prevent scale buildup, it is effective to prevent water retention so that any scale deposition is washed away by the water flow. However, the grooves in Patent Document 1 are filled with an ion exchange membrane that has absorbed water, making it difficult to prevent water retention. Also, electrolytic cells are known that have a mesh electrode interposed between the cathode and the ion exchange membrane, but water collides with the mesh electrode and flows irregularly through the gaps between them, making it difficult to prevent water retention.

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an electrolyzed water generating apparatus having an electrolytic cell configured to suppress the buildup of scale on the cathode. [Means for solving the problem]

[0009] The electrolyzed water generating device of the invention of claim 1 comprises an electrolytic cell formed by stacking a flat anode, a mesh electrode, a catalytic electrode, an ion exchange membrane, and a flat cathode, each having an opening in the center, to form a central passage portion through which the openings communicate, and generates electrolyzed water by electrolyzing water that flows between the anode and the cathode from the outer periphery of the electrolytic cell toward the central passage portion or from the central passage portion toward the outer periphery of the electrolytic cell, characterized in that the cathode has a water flow groove formed on the side facing the ion exchange membrane to allow water to flow between the central passage portion and the outer periphery, and the water flow groove is composed of two types of grooves with different cross-sectional areas.

[0010] According to the above configuration, by forming the water passage grooves with two types of grooves with different cross-sectional areas on the side of the cathode facing the ion exchange membrane, it is possible to equalize the pressure loss in each water passage of the water passage grooves. Therefore, water flows equally in each passage, preventing water stagnation and thereby preventing scale buildup on the cathode.

[0011] The electrolytic water generating device of the invention of claim 2 is characterized in that, in the invention of claim 1, the cathode, the ion exchange membrane, the catalytic electrode, the mesh electrode, and the anode are each rectangular, the water flow groove is composed of a first groove extending along the diagonal of the cathode and a second groove extending from the outer periphery of the cathode to the first groove perpendicular to this periphery, the cross-sectional area of ​​the second groove is constant, and the cross-sectional area of ​​the first groove is larger than the cross-sectional area of ​​the second groove. According to the above configuration, the water passage grooves can be formed by the first groove and the second groove so that the pressure loss is equal in all water passages of the cathode water passage grooves, thereby preventing water from accumulating in all water passages and suppressing scale buildup in the cathode.

[0012] The electrolyzed water generating device of the invention of claim 3 is the invention of claim 2, characterized in that the cross-sectional area of ​​the first groove increases from the outer periphery toward the center of the cathode. According to the above configuration, the water passage grooves can be formed so that the pressure loss is equal between the water passages where the first and second grooves are connected, which prevents water from accumulating in any of the water passages and prevents scale buildup on the cathode.

[0013] The electrolytic water generating device of the invention of claim 4 is characterized in that, in the invention of claim 2 or 3, the cathode has a recess in the central portion corresponding to the central passage portion, in which a portion of the first groove and a portion of the second groove are connected. According to the above configuration, water passing through different water passages can be mixed in the recess to prevent backflow in other water passages, or water can be evenly distributed from the recess to the different water passages, thereby preventing water from accumulating in any of the water passages and preventing scale buildup on the cathode. [Effects of the Invention]

[0014] The electrolyzed water generator of the present invention can suppress the buildup of scale on the cathode of the electrolytic cell, thereby suppressing a decrease in the efficiency of electrolyzed water production and improving the durability of the electrolyzed water generator. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is an external perspective view of a water electrolysis apparatus according to an embodiment of the present invention. [Figure 2] 2 is a plan view of the water electrolysis apparatus of FIG. 1, viewed from the water inlet side. FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. [Figure 4] FIG. 2 is an exploded view of the water electrolysis device of FIG. [Figure 5] FIG. 5 is an exploded view of the electrolysis cell of FIG. [Figure 6] FIG. 2 is a plan view showing the water passage grooves on the ion exchange membrane side of the cathode. [Figure 7] FIG. 10 is a plan view showing a water passage groove on the ion exchange membrane side of a cathode having a recess corresponding to a central passage portion. [Figure 8] FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 7. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, the mode for carrying out the present invention will be described based on examples. [Example]

[0017] As shown in Figures 1, 2, 3, and 4, electrolyzed water generator 1 has an electrolytic cell 10 housed in a case 4 having a water inlet 2 and a water outlet 3, and power lines 9a and 9b are connected to electrolytic cell 10 from the outside to supply power for electrolyzing water. Case 4 is made up of a first case 5 having water inlet 2 and a second case 6 having water outlet 3. Water pipes or hoses (not shown) are connected to water inlet 2 and water outlet 3, respectively.

[0018] In the case 4, water introduced from the water inlet 2 flows, for example, as indicated by arrow A1, spreading out toward the outer periphery of the electrolytic cell 10, then changes direction as indicated by arrow A2, and circulates within the electrolytic cell 10, converging from the outer periphery toward the center of the electrolytic cell 10. Then, the water flows out of the case 4 from the water outlet 3 as indicated by arrow A3.

[0019] At this time, a portion of the water flowing through the electrolysis cell 10 is electrolyzed in the electrolysis cell 10 to generate electrolyzed water. The electrolyzed water is, for example, ozone water or hypochlorous acid water, and has a bactericidal effect. The water inlet 2 is equipped with a water governor 2a to keep the water flow rate constant, and electrolyzed water of a constant quality (concentration) is generated.

[0020] The electrolytic cell 10 is fixed to the second case 6, which has the water discharge portion 3, by a retaining plate 7, which is fixed with multiple screws 7a. The retaining plate 7 guides water introduced from the water inlet 2 of the first case 5 toward the outer periphery of the electrolytic cell 10. The first case 5 is fixed to the second case 6, to which the electrolytic cell 10 is fixed, with multiple screws 4a, with a gasket 8 sandwiched between them.

[0021] Next, the electrolytic cell 10 will be described. As shown in FIG. 5 , the electrolytic cell 10 is formed into a rectangular parallelepiped by stacking an anode 11, a mesh electrode 12, a catalytic electrode 13, an ion exchange membrane 14, and a cathode 15, all of which are equivalent in size. The cathode 15 is a rectangular flat plate with a side length of, for example, several tens of millimeters. The anode 11, the mesh electrode 12, the catalytic electrode 13, and the ion exchange membrane 14 are also rectangular flat plates, each with a rectangular opening in the center. The electrolytic cell 10 has a central passage 16 that connects the opening 11 a of the anode 11, the opening 12 a of the mesh electrode 12, the opening 13 a of the catalytic electrode 13, and the opening 14 a of the ion exchange membrane 14.

[0022] The catalytic electrode 13 carries a catalyst for promoting the electrolysis of water. The mesh electrode 12 is formed of metal wires made of, for example, titanium or stainless steel, into a mesh shape with fine voids that communicate with the outside. The anode 11 has a terminal portion 11b extending from one end of the anode 11 for connection to the power line 9a. The cathode 15 has a terminal portion 15a extending from one end of the cathode 15 for connection to the power line 9b. These terminal portions 11b, 15a are formed so as not to overlap when stacked.

[0023] As shown in Fig. 4, the second case 6 has a positioning portion 6a for positioning the electrolysis cell 10, which is formed by multiple protrusions protruding inward from the case 4, and a rectangular opening 3a corresponding to the central passage portion 16 of the electrolysis cell 10. The central passage portion 16 and the water discharge portion 3 are in communication with each other through this opening 3a. In the second case 6, an anode 11, a mesh electrode 12, a catalytic electrode 13, an ion exchange membrane 14, and a cathode 15 are stacked in this order from the water discharge portion 3 side, and a retaining plate 7 that restrains these in the stacking direction is fixed to the second case 6. Corresponding power lines 9a, 9b are fastened and fixed to the terminal portions 11b, 15a, and the first case 5 is fixed to the second case 6 with a packing 8 sandwiched therebetween.

[0024] The positioning portion 6a of the second case 6 is formed by multiple protrusions that protrude inward from the case 4, and therefore the outer periphery of the electrolytic cell 10 is not blocked by the positioning portion 6a. Therefore, water introduced from the water inlet 2 toward the outer periphery as indicated by arrow A1 in Figure 3 changes direction as indicated by arrow A2 and can flow between the anode 11 and the cathode 15 from the outer periphery of the electrolytic cell 10 toward the central passage portion 16 of the electrolytic cell 10.

[0025] By applying an external voltage between the anode 11 and the cathode 15 of the electrolysis cell 10, a portion of the water flowing between the anode 11 and the cathode 15 is electrolyzed to generate electrolyzed water. Then, as indicated by arrow A3, the electrolyzed water collected in the central passage 16 of the electrolysis cell 10 flows out of the case 4 through the water discharge part 3.

[0026] Although not shown in the figures, it is possible to reverse the direction of water flow by switching the roles of the water outlet section 3 and the water inlet section 2, i.e., to make water flow from the central passage section 16 towards the periphery of the electrolytic cell 10 between the anode 11 and cathode 15 of the electrolytic cell 10.

[0027] In the vicinity of the cathode 15, a reaction occurs between hydroxide ions generated by the electrolysis of water and mineral components contained in the water, resulting in the deposition of insulating scale such as calcium carbonate or magnesium hydroxide. If this scale accumulates on the side of the cathode 15 facing the ion exchange membrane 14, it inhibits the production of electrolyzed water. Therefore, in constant voltage operation, in which a constant voltage is applied between the anode 11 and the cathode 15, the quality (concentration) of the electrolyzed water decreases. Furthermore, in constant current operation, in which the applied voltage is adjusted so that a constant current flows, an increase in the applied voltage promotes reactions in areas where scale has not accumulated, resulting in accelerated scale accumulation.

[0028] To prevent scale buildup, it is effective to ensure that any scale that does deposit is washed away by the water flow. To prevent water from accumulating near the cathode 15 and prevent scale buildup on the cathode 15, a water passage groove 20 is formed on the side of the cathode 15 facing the ion exchange membrane 14, as shown in Figures 3 and 6. This water passage groove 20 is formed large enough to prevent blockage due to volume expansion caused by water absorption by the ion exchange membrane 14.

[0029] The water passage grooves 20 are composed of two types of grooves: first grooves 21 that extend along the diagonal of the cathode 15, and second grooves 22 that extend from the outer periphery of the cathode 15 to the first grooves 21 so as to be perpendicular to this periphery. The cross-sectional shapes of the first grooves 21 and second grooves 22 are semicircular with diameters r1 and r2, respectively. The cross-sectional area of ​​the groove is the area of ​​a cross section perpendicular to the direction in which the groove extends.

[0030] The cross-sectional area of ​​the second grooves 22 is constant, i.e., r2 is set to a predetermined value. A plurality of second grooves 22 having this constant cross-sectional area are formed at equal intervals in the cathode 15. The cross-sectional area of ​​the first grooves 21 is larger than the cross-sectional area of ​​the second grooves 22, i.e., r1>r2. The plurality of first grooves 21 are formed so that the cross-sectional area increases (so that r1 increases) from the outer periphery (corner) of the cathode 15 toward the center. Note that the reference numerals of some of the second grooves 22 are omitted in FIG. 6.

[0031] Next, the setting of the cross-sectional area of ​​the first groove 21 will be described. Generally, the pressure loss due to friction in a water pipe can be calculated by the following equation (1) (Darcy-Weisbach equation) as the head loss h f It can be expressed as [m]. h f =fLV 2 / (2gD H ) ···(1) f is the friction loss coefficient of the pipe, L is the pipe length [m], V is the cross-sectional average flow velocity [m / s], and g is the gravitational acceleration [m / s 2 ], D H is the hydraulic diameter [m]. Head loss h fis the pipe length (L) and the square of the cross-sectional average flow velocity (V 2 ) and is proportional to the hydraulic diameter (D H ) In addition, if the piping is circular, the hydraulic diameter is equal to the inner diameter of the circular pipe.

[0032] When water flows through water passage grooves 20 from the outer periphery of cathode 15 toward the center, the water passage path includes a path that passes only through first grooves 21 (e.g., path P1) and paths that merge from second grooves 22 to first grooves 21 (e.g., paths P2, P3, etc.). These merging paths have different merging positions (connection positions of second grooves 22 and first grooves 21), and therefore the lengths of second grooves 22 and first grooves 21 in each path are different. The cross-sectional area of ​​first grooves 21 is set based on the above formula (1) so that the flow rate of water is equal in all water passages to prevent stagnation, that is, so that pressure loss is equal in all water passages. Note that, for the sake of water passage grooves 20, cathode 15 is preferably square or rectangular, close to a square.

[0033] For example, when the length of first groove 21 from the outer periphery to the joining position of first groove 21 and second groove 22 is L1 and the length of second groove 22 is L2, the diameter (r1) of first groove 21 can be set so that L1:L2=r1:r2 at each joining position. The diameter of first groove 21 between the joining positions is set so that it becomes larger from the outer periphery toward the center of cathode 15 to correspond to the diameter set at the joining position, forming a smoothly continuous groove, and the cross-sectional area of ​​first groove 21 increases from the outer periphery toward the center of cathode 15.

[0034] In this way, the cross-sectional area of ​​first groove 21 increases in response to the increase in the flow rate of first groove 21 due to the water joining from second groove 22, making it possible to equalize the pressure loss in any water flow path. Furthermore, because first groove 21 and second groove 22 each extend linearly, water can flow linearly and not stagnate. Furthermore, even when water flows from the center toward the outer periphery of cathode 15, the pressure loss is equalized regardless of the water flow path.

[0035] Furthermore, because the multiple second grooves 22, each with a constant cross-sectional area, are formed at equal intervals, the uneven distribution of the water passage grooves 20 in the cathode 15 is reduced. For example, the uneven distribution of the water passage grooves 20 can be reduced compared to when multiple grooves with a constant cross-sectional area are formed radially from the center to the periphery of the cathode 15, with the grooves being more densely packed toward the center. Therefore, water can be electrolyzed evenly within the electrolytic cell 10, preventing a decrease in the quality of the electrolyzed water. Furthermore, because no areas prone to scale deposition are formed, a decrease in the durability of the electrolyzed water generator 1 can be prevented.

[0036] As shown in Figures 7 and 8, a recess 23 may be formed in the center of the cathode 15 to correspond to the central passage portion 16. In Figures 7 and 8, the reference numerals of the second grooves 22 are also omitted. All of the first grooves 21 and some of the multiple second grooves 22 are connected to the recess 23. As described above, the cross-sectional areas of the grooves are set so that the pressure loss is equal in all water flow paths. Water passing through different water flow paths can be mixed in the recess 23 to prevent backflow into other water flow paths. When the flow directions are opposite, the water can be evenly distributed from the recess 23 to the different water flow paths. Although not shown, multiple protrusions that do not obstruct water flow may also be formed in the first case 5. The electrolytic cell 10 may be fixed while maintaining its stacked state by the multiple protrusions of the first case 5 and the second case 6, thereby eliminating the need for a retaining plate 7. Although also not shown, the recess 23 may be formed by, for example, a retaining plate 7 that closes an opening penetrating the cathode 15 and one end of the opening.

[0037] The operation and effects of the electrolyzed water generator 1 will now be described. The electrolyzed water generator 1 has an electrolysis cell 10 formed by stacking a flat anode 11, a mesh electrode 12, a catalytic electrode 13, an ion exchange membrane 14, and a flat cathode 15, each of which has an opening in the center, and forming a central passage 16 through which the openings of these electrodes communicate. Electrolyzed water is produced by electrolyzing water that flows between the anode 11 and the cathode 15, from the outer periphery of the electrolysis cell 10 toward the central passage 16 or from the central passage 16 toward the outer periphery of the electrolysis cell 10. A water passage groove 20 is formed in the cathode 15 on the side facing the ion exchange membrane 14, allowing water to flow between the central passage 16 and the outer periphery. The water passage groove 20 is composed of two types of grooves (first groove 21 and second groove 22) with different cross-sectional areas.

[0038] By forming water passage groove 20 with two types of grooves, it is possible to make the pressure loss equal in all water passage paths of water passage groove 20. Therefore, water flows equally in all flow paths, and water stagnation can be suppressed, thereby suppressing the accumulation of scale on cathode 15.

[0039] The cathode 15, ion exchange membrane 14, catalytic electrode 13, mesh electrode 12, and anode 11 are each rectangular, and the water passage grooves 20 are composed of first grooves 21 extending along the diagonal of the cathode 15 and second grooves 22 extending from the outer periphery of the cathode 15 to the first grooves 21 so as to be perpendicular to this periphery. The cross-sectional area of ​​the second grooves 22 is constant, and the cross-sectional area of ​​the first grooves 21 is larger than the cross-sectional area of ​​the second grooves 22. This makes it possible to make the pressure loss equal in all water passage paths of the water passage grooves 20.

[0040] Furthermore, the cross-sectional area of ​​first groove 21 increases from the outer periphery toward the center of cathode 15. This allows water passage groove 20 to be formed so that the pressure loss is equal between the water passage paths where first groove 21 and second groove 22 are connected to each other.

[0041] Cathode 15 has a recess 23 in the center corresponding to central passage 16, where a portion of first groove 21 and a portion of second groove 22 are connected. Therefore, water that has passed through different water passages can be mixed in recess 23 to prevent backflow into other water passages, or water can be evenly distributed from recess 23 to the different water passages. Therefore, water flows equally through all water passages, preventing water from stagnating, and thus preventing scale buildup on cathode 15.

[0042] In addition, a person skilled in the art can implement the present invention in a form in which various modifications are added to the above-described embodiment without departing from the spirit of the present invention, and the present invention includes such modifications. [Explanation of symbols]

[0043] 1: Electrolyzed water generator 2: Water entry section 3: Water outlet 4: Case 5: First case 6: Second case 7: Retaining plate 8: Packing 9a,9b: Power line 10: Electrolytic cell 11:Anode 11a: Opening 12: Mesh electrode 12a: opening 13: Catalyst electrode 13a: Opening 14: Ion exchange membrane 14a: Opening 15: Cathode 15a:Terminal section 20: Water channel 21: 1st groove 22: 2nd groove 23: Recess

Claims

1. An electrolyzed water generator comprising an electrolytic cell in which a flat anode, a mesh electrode, a catalytic electrode, an ion exchange membrane, and a flat cathode, each having an opening in the center, are stacked to form a central passage through which the openings communicate, and which generates electrolyzed water by electrolyzing water that flows between the anode and the cathode from the outer periphery of the electrolytic cell toward the central passage or from the central passage toward the outer periphery of the electrolytic cell, a water passage groove is formed in the cathode on the side facing the ion exchange membrane, for allowing water to flow between the central passage portion and the outer periphery; The electrolytic water generating device is characterized in that the water flow groove is composed of two types of grooves with different cross-sectional areas.

2. the cathode, the ion exchange membrane, the catalytic electrode, the mesh electrode, and the anode are each rectangular; The electrolytic water generating device described in claim 1, characterized in that the water flow groove is composed of a first groove extending along the diagonal line of the cathode and a second groove extending from the outer periphery of the cathode to the first groove perpendicular to this periphery, the cross-sectional area of ​​the second groove being constant, and the cross-sectional area of ​​the first groove being larger than the cross-sectional area of ​​the second groove.

3. 3. The electrolyzed water generating device according to claim 2, wherein the cross-sectional area of ​​the first groove increases from the outer periphery toward the center of the cathode.

4. 4. The electrolytic water generating device according to claim 2, wherein the cathode has a recess in the center corresponding to the central passage portion, in which the first groove and a part of the second groove are connected.

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